Fuel compositions



FUEL COMPOSITIONS Allen E. Brehm, Griflith, Ind., and Ellis K. Fields, Chicago, 111., assignors to Standard Oil Company, Chicago, 111., a corporation of Indiana No Drawing. Application April 18, 1955, Serial No. 502,212

Claims. (Cl. 44-71) Our invention relates to distillate fuel compositions, particularly light hydrocarbon distillate fuels such as gasoline, which contain an N-alkyl-N, N-di(carboxymethyl) urea.

We have discovered that N-alkyl-N', N'-di(carboxymethyl) ureas have special value as rust inhibitors in light distillate hydrocarbon fuels. These materials combine excellent capacity for imparting rust preventative properties to light petroleum distillates with effectiveness in diminishing corrosivity of light petroleum distillates towards metals.

The protection of aviation gasoline, in particular, against rust accumulation is a serious problem because of the hazard created by rust and sediment carry-over into the fuel system of operating aircraft. Although hydrocarbon fuels are not themselves corrosive in the sense of rusting ferrous metal surfaces, the moisture normally present in gasoline by pick-up from the atmosphere and from tank bottoms is the cause of considerable rusting of ferrous metal surfaces in the tanks, lines and surfaces of storage, shipping, handling and engine accessory equipment. The water bottoms usually carried in storage and shipping containers aggravates the problem. The water layer contains sufiicient dissolved oxygen to cause rusting at a more rapid rate. This rust tends to flake off and may be carried as sediment into the gasoline layer. Also, the water layer in contact with the gasoline layer tends to leach out Water soluble inhibitors from the gasoline, making the problem of rust prevention by this means more difficult.

Corrosivity of light hydrocarbon distillates as such to metal surfaces, particularly copper, is a different problem and usually is related to the presence of sulfur or other corrosive compounds in the oil. It is an unusual and distinctive property of the inhibitors of our invention that they have value in inhibiting not only rusting of metal surfaces by oxidative corrosion induced by moisture associated with fuels but also the direct corrosive attack of the fuels on metals such as copper.

The new inhibitors are characterized structurally as follows:

RNH( IN(CHz%OH) Where R is an aliphatic or substituted aliphatic group containing to 40 carbon atoms, preferably in a straight chain.

The use of the octadecyl derivative is a particularly advantageous form of the invention because it provides a long straight chain hydrocarbon group which imparts good oil solubility and which, in conjunction with the polar carboxy groups, provides close molecular packing in film formation and unusual film strength. Other higher alkyl derivatives such as the dodecyl and hexadecyl derivatives, for example, may be readily produced from available raw materials and are highly effective. It is not strictly necessary that the aliphatic group be a straight chain, for other higher hydrocarbon groups such as long iatented Nov. 27, 1956 2 1 chain, but methyl branched, hydrocarbon groups derived by olefin polymerization appear to have value, c. g. polybutenes. Hydrocarbon groups derived from waxes, with or Without some ring substitution also appear suitable, and the substitution of an aromatic ring, particularly so that para-orientation of the alkyl and polar groupings results, may enhance oil solubility. In addition to the substituted urea inhibitors containing free carboxy groups, simple derivatives thereof such as esters with lower alcohols, amides with lower alkylamines as well as oil soluble salts have value in light distillate fuels.

The new compositions may be made by reacting a long chain isocyanate with imino diacetic acid, or preferably, its salts. The use of approximately equimolar proportions at a temperature of about 20 to 100 C., for a reaction period of about 10 minutes to 6 hours is suitable. The reaction may be conducted in the presence or absence of a solvent or diluent, e. g. benzene, or a lubricating oil distillate.

In use, the new inhibitors are added to light distillate fuels in small concentrations, usually in the range of about 0.0001 to 0.1 weight percent. Inhibitors may be handled in the form of concentrates in hydrocarbon distillates, which 'are then blended back in the finished fuel composition to the effective concentration. Conventional additives such as tetraethyl lead, anti-oxidants, gum inhibitors and the like also will be normally present in the finished blend. The distillate base stocks are conventionally produced by crude oil fractionation, cracking processes and special conversions such as reforming, alkylation, polymerization and the like. The boiling range of the distillate base stocks in the gasoline range approximates 100 400 F. while that of diesel fuels and heating oils may be in the range of about 350-700 F.

The following examples illustrate preparation of a substituted urea inhibitor according to the invention and its evaluation as a rust inhibitor and corrosion inhibitor in gasoline.

Example I A mixture of 59 grams (0.2 mole) of octadecyl isocyanate and 39 grams (0.2 mole) of disodium imino diacetate monohydrate was stirred and heated slowly. At C. reaction took place with the evolution of heat, and the whole mass solidified. It was broken up, dissolved in 500 ml. of Warm water, and neutralized with 25 ml. concentrated hydrochloric acid. The white precipitate was collected on a filter, washed with cold water, and dried. The yield was 81 grams of 94% of The analysis calculated for C23H44N2O5 was: C, 64.55; H, 10.28; N, 6.54. Found: C, 64.75; H, 10.26; N, 6.62. Recrystallized from hexane, the compound melted at 83.5 -84 C.

Example 11 The product of Example I was tested at concentrations of 5 pounds and 25 pounds per 1,000 barrels (0.002 and 0.01 Weight percent respectively) in a finished motor gasoline for rust protection.

The rust test used is as follows: SAE 1020 steel panels /2 x 6 x 4; inches are belt sanded clean of discoloration and pits and then cleaned with hot petroleum naphtha followed by hot acetone. They are placed in ml. of the test fuel in a tall form 4 oz. bottle where they are allowed to stand for /2 hour. After this contact 10 m1. of tap water are added and the capped bottle is rolled for 1 minute. The bottle is then placed in an upright position. Strips are evaluated in the fuel layer from 30 minutes to 24 hours later. The length of exposure is not too important as long as a control is included with each set. In evaluating the panels, a spot of rust refers to an area l-3 mm. in diameter, and a speck refers to an area of rust less than 1 mm. in diameter. The test data follow:

Rust in Rust in Stock Gasoline Water Layer Layer Gasoline A 6883151118 A +5 Lb. Product Ex. I/l,000 bhls.

Gasoline A Lb. Commercial Inhibitor 70%.

(Dilinoleic acid) [1,000 bbls. D0 s ots--. 80%.

Gasoline B 20% Slight. Gasoline B +5 Lb. Product Ex. I/1,000 bbls... No rust--- v. slight. Gasoline B Lb. Product Ex. I/1,000 bbls .do None.

From the above data it will be noted that a product typical of the invention gave excellent protection in the gasoline layer, but the outstanding point to be observed is the significant improvement in protection afforded in the water layer since this protection is very diflicult to obtain with an oil soluble inhibitor.

Example III The product of Example I was tested for ability to inhibit petroleum naphtha against corrosive attack of copper. The test was made according to the method of ASTM D-235, and the copper strips were rated by the ASTM copper strip corrosion scale used for gasoline. The results were as follows:

Stock D235 1008 1. Stanisol Petroleum Solvent Naptha 5+ 2. 1+.003 wt. Percent Product Example I 4 3. 1+.05 wt. Percent Product Example I 0 We claim: 1. A fuel composition which comprises essentially a light hydrocarbon distillate and about 0.0001 to 0.1 weightv percent of an oil soluble N-alkyl-N, '-di(carboxymethyl) urea in which the alkyl group is a long chain containing 10 to 40 carbon atoms.

2. The composition of claim 1 in which the hydrocarbon distillate is gasoline.

3. The composition of'claim 1 in which the urea is N-dodecyl-N', N'-di(carboxymethyl) urea. 1

4. The composition of claim 1 in which the urea N-hexadecyl-N', N-di(carboxymethyl) urea.

5. The composition of claim 1 in which the urea is N-octadecyl-N, N-di(carboxymethyl) urea.

References Cited in the file of this patent UNITED STATES PATENTS 2,368,604 White Jan. 30, 1945 2,514,508 Nunn July 11, 1950 2,683,083 Hill July 6, 1954 2,710,841

Swakon et al June 14, 1955 

1. A FUEL COMPOSITION WHICH COMPRISES ESSENTIALLY A LIGHT HYDROCARBON DISTILLATE AND ABOUT 0.0001 TO 0.1 WEIGHT PERCENT OF AN OIL SOLUBLE N-ALKYL-N'',N''-DI(CARBOXYMETHYL) UREA IN WHICH THE ALKYL GROUP IS A LONG CHAIN CONTAINING 10 TO 40 CARBON ATOMS. 